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| | #include "pthread_impl.h"
volatile size_t __pthread_tsd_size = sizeof(void *) * PTHREAD_KEYS_MAX;
void *__pthread_tsd_main[PTHREAD_KEYS_MAX] = { 0 };
static void (*keys[PTHREAD_KEYS_MAX])(void *);
static pthread_rwlock_t key_lock = PTHREAD_RWLOCK_INITIALIZER;
static pthread_key_t next_key;
static void nodtor(void *dummy)
{
}
static void dirty(void *dummy)
{
}
struct cleanup_args {
pthread_t caller;
int ret;
};
static void clean_dirty_tsd_callback(void *p)
{
struct cleanup_args *args = p;
pthread_t self = __pthread_self();
pthread_key_t i;
for (i=0; i<PTHREAD_KEYS_MAX; i++) {
if (keys[i] == dirty && self->tsd[i])
self->tsd[i] = 0;
}
/* Arbitrary choice to avoid data race. */
if (args->caller == self) args->ret = 0;
}
extern hidden weak void __pthread_key_delete_synccall(void (*f)(void *), void *p);
static int clean_dirty_tsd(void)
{
struct cleanup_args args = {
.caller = __pthread_self(),
.ret = EAGAIN
};
__pthread_key_delete_synccall(clean_dirty_tsd_callback, &args);
return args.ret;
}
int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
{
pthread_key_t j = next_key;
pthread_t self = __pthread_self();
int found_dirty = 0;
/* This can only happen in the main thread before
* pthread_create has been called. */
if (!self->tsd) self->tsd = __pthread_tsd_main;
/* Purely a sentinel value since null means slot is free. */
if (!dtor) dtor = nodtor;
pthread_rwlock_wrlock(&key_lock);
do {
if (!keys[j]) {
keys[next_key = *k = j] = dtor;
pthread_rwlock_unlock(&key_lock);
return 0;
} else if (keys[j] == dirty) {
found_dirty = 1;
}
} while ((j=(j+1)%PTHREAD_KEYS_MAX) != next_key);
/* It's possible that all slots are in use or __synccall fails. */
if (!found_dirty || clean_dirty_tsd()) {
pthread_rwlock_unlock(&key_lock);
return EAGAIN;
}
/* If this point is reached there is necessarily a newly-cleaned
* slot to allocate to satisfy the caller's request. Find it and
* mark any additional previously-dirty slots clean. */
for (j=0; j<PTHREAD_KEYS_MAX; j++) {
if (keys[j] == dirty) {
if (dtor) {
keys[next_key = *k = j] = dtor;
dtor = 0;
} else {
keys[j] = 0;
}
}
}
pthread_rwlock_unlock(&key_lock);
return 0;
}
int __pthread_key_delete_impl(pthread_key_t k)
{
pthread_rwlock_wrlock(&key_lock);
keys[k] = dirty;
pthread_rwlock_unlock(&key_lock);
return 0;
}
void __pthread_tsd_run_dtors()
{
pthread_t self = __pthread_self();
int i, j;
for (j=0; self->tsd_used && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
pthread_rwlock_rdlock(&key_lock);
self->tsd_used = 0;
for (i=0; i<PTHREAD_KEYS_MAX; i++) {
void *val = self->tsd[i];
void (*dtor)(void *) = keys[i];
self->tsd[i] = 0;
if (val && dtor && dtor != nodtor && dtor != dirty) {
pthread_rwlock_unlock(&key_lock);
dtor(val);
pthread_rwlock_rdlock(&key_lock);
}
}
pthread_rwlock_unlock(&key_lock);
}
}
weak_alias(__pthread_key_create, pthread_key_create);
|